Non-aqueous electrolyte battery

ABSTRACT

A non-aqueous electrolyte battery of the present invention includes a non-aqueous electrolyte containing a lithium salt, a cyclic sultone derivative, and an acid anhydride, wherein the non-aqueous electrolyte contains the cyclic sultone derivative in an amount of 0.3 to 3% by mass and the non-aqueous electrolyte contains the acid anhydride in an amount of 0.3 to 3% by mass. Furthermore, the non-aqueous electrolyte battery includes at least one selected from a cyclic sultone derivative and an acid anhydride, and an electrolyte salt. The electrolyte salt contains lithium salt A and lithium salt B. The lithium salt A is at least one selected from LiBF 4 , LiPF 6 , LiAsF 6 , and LiSbF 6 , and the lithium salt B is a lithium salt other than the lithium salt A. The electrolyte contains the lithium salt A in an amount of 2 mol % or more.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a non-aqueous electrolytebattery, and more specifically, to a non-aqueous electrolyte batterysuitable for use in a high-temperature atmosphere.

[0003] 2. Description of the Related Art

[0004] Recently, there is an increasing demand for a battery that can beused as a power source for equipment used in a high-temperatureatmosphere (higher than 100° C.), such as a pressure sensor in a tire. Apotential candidate for such a battery includes a non-aqueouselectrolyte battery such as a lithium primary battery and a lithium ionsecondary battery.

[0005] As the non-aqueous electrolyte battery to be used for theabove-mentioned purpose, a lithium primary battery using manganesedioxide or graphite fluoride as a positive active material and lithiumor a lithium alloy as a negative electrode, and a lithium ion secondarybattery using lithium cobaltate or lithium manganate as a positiveactive material and a carbon material as a negative electrode areconsidered to be suitable due to their excellent load characteristicsand low-temperature characteristics. However, when these batteries areleft or used at a high temperature, a carbonic ester (propylenecarbonate, ethylene carbonate, methyl ethyl carbonate, etc.) that is asolvent of an electrolyte reacts with the positive active material togenerate gas such as carbon dioxide, which causes the batteries toexpand.

[0006] In particular, when a manganese-containing oxide such asmanganese dioxide is used as a positive active material, theabove-mentioned generation of gas becomes conspicuous due to thecatalyst function of the positive active material. In a temperatureregion higher than 100° C., such a problem becomes more serious.Furthermore, the following also is found: when a battery discharged byabout 50% or more is used in a high-temperature atmosphere or left for along period of time, gas is generated suddenly due to hydrogen andhydrocarbon such as methane, which causes the battery to expand. In thiscase, the generation of gas is presumed to be caused by the reactionbetween a solvent of an electrolyte and lithium at a negative electrode,as well as the reaction between the solvent of the electrolyte and thepositive active material.

[0007] On the other hand, in the case of an ordinary coin-type primarybattery, in order to seal the battery, packing made of polypropylene(PP) (which often is referred to as a “gasket”) mainly is used.Polypropylene is a packing material with sufficient reliability forgeneral use and is inexpensive. However, in a temperature region higherthan 100° C. that is close to the melting point of polypropylene,polypropylene is softened to make it impossible to obtain sufficientstrength. Therefore, polypropylene is not suitable as a packing materialfor a battery intended for a high temperature.

[0008] As a packing material intended for a high temperature, asdescribed in JP 8(1996)-153500 A, a heat-resistant resin having amelting point of 240° C. or higher (e.g., atetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA),polyphenylene sulfide, and polyether ether ketone) was studied.

[0009] An olefin-type packing material such as polypropylene, which hasbeen used generally, allows gas generated in a battery to passtherethrough gradually to dissipate out of the battery, whereby anincrease in pressure in the battery is alleviated. The packing composedof the above-mentioned heat-resistant resin has sufficient durabilityeven at a high temperature; however, transmittance of gas is very small.Therefore, gas accumulates in the battery, and the battery expands dueto an increase in pressure. Needless to say, in the case where glasshermetic seal having hermeticity higher than that of sealing with theheat-resistant packing, the expansion of the battery becomes furtherconspicuous.

[0010] There are various reasons for avoiding expanding a battery. Whena battery expands, equipment to be used is damaged, and the contactbetween electrodes and a current collector becomes insufficient, whichdecreases battery performance and impairs reliability of the battery.

[0011] In order to solve the above-mentioned problem, JP 11(1999)-162511A (EP 1030399), JP 2000-3724 A (U.S. Pat. No. 6,033,809), JP 2000-123868A, JP 2000-323171 A, and the like disclose the addition of a cyclicsultone derivative such as 1,3-propanesultone to an electrolyte for thepurpose of enhancing cycle characteristics of a non-aqueous electrolytebattery and suppressing the generation of gas. Furthermore, JP4(1992)-355065 A (U.S. Pat. No. 5,296,319), JP 7(1995)-122297 A, and thelike disclose that an acid anhydride is added to an electrolyte toreduce the amount of moisture in the electrolyte so as to enhancestorage characteristics of a battery at a high temperature. Theseadditives respectively are relatively effective for suppressing thegeneration of gas in a battery at a temperature of about 60° C. to 80°C. and enhancing storage characteristics.

[0012] In atmospheres having temperatures of 100° C. or higher, theseadditives are not effective enough for the above purpose.

[0013] Furthermore, it also is found that although the above-mentionedadditives are sufficiently effective to a battery before discharging orwith a small discharge depth, they do not exhibit effects as expectedwith respect to the battery that has been discharged to some degree.

SUMMARY OF THE INVENTION

[0014] In one aspect, the present invention relates to a non-aqueouselectrolyte battery including a positive electrode, a negativeelectrode, a separator, and a non-aqueous electrolyte, wherein thenon-aqueous electrolyte contains a lithium salt, a cyclic sultonederivative, and an acid anhydride, the non-aqueous electrolyte containsthe cyclic sultone derivative in an amount of 0.3 to 3% by mass, and thenon-aqueous electrolyte contains the acid anhydride in an amount of 0.3to 3% by mass.

[0015] In one aspect, the present invention relates to a non-aqueouselectrolyte battery including a positive electrode, a negativeelectrode, a separator, and a non-aqueous electrolyte, wherein thenon-aqueous electrolyte contains at least one selected from the groupconsisting of a cyclic sultone derivative and an acid anhydride, and anelectrolyte salt, the electrolyte salt contains lithium salt A andlithium salt B, the lithium salt A is at least one selected from thegroup consisting of LiBF₄, LiPF₆, LiAsF₆, and LiSbF₆, the lithium salt Bis a lithium salt other than the lithium salt A, and the electrolytesalt contains the lithium salt A in an amount of 2 mol % or more.

[0016] In one aspect, the present invention relates to a non-aqueouselectrolyte battery including a positive electrode, a negativeelectrode, a separator, a non-aqueous electrolyte, and a sealing member,wherein the non-aqueous electrolyte contains a solvent and a cyclicsultone derivative, the solvent contains an ether having a boiling pointof 120° C. or higher, the non-aqueous electrolyte contains the cyclicsultone derivative in an amount of 0.5 to 5% by mass, and the sealingmember includes a packing made of a heat-resistant resin or glasshermetic seal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 shows a cross-sectional view schematically showing anexample of a non-aqueous electrolyte battery of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention provides a non-aqueous electrolyte batterysuitable for use in a high-temperature atmosphere by decreasing thegeneration of gas in the battery to suppress the expansion of thebattery while keeping excellent load characteristics and low-temperaturecharacteristics peculiar to the non-aqueous electrolyte battery.Furthermore, in certain embodiments, the above-mentioned effects can bemaintained irrespective of a discharge depth of the non-aqueouselectrolyte battery.

[0019] Other advantages of the present embodiment will become apparentto those skilled in the art upon reading and understanding the followingdetailed description with reference to the accompanying figures.

[0020] In one embodiment, a non-aqueous electrolyte is obtained bydissolving an electrolyte salt in a solvent or a mixed solvent of atleast two kinds selected from the group consisting of a cyclic carbonicester such as propylene carbonate, ethylene carbonate, butylenecarbonate, and vinylene carbonate; a chain carbonic ester such asdimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; andan ether such as 1,2-dimethoxyethane, diglime (diethylene glycoldimethyl ether), triglime (triethylene glycol dimethyl ether),tetraglime (tetraethylene glycol dimethyl ether), methoxyethoxyethane,1,2-diethoxyethane, and tetrahydrofuran. In particular, as carbonicester, propylene carbonate, ethylene carbonate, butylene carbonate, andthe like, having a boiling point of 120° C. or higher, are preferable.Furthermore, as ether, diethoxyethane, diglime, and the like, having aboiling point of 120° C. or higher, are preferable.

[0021] When the molecular weight of ether is increased, the freezingpoint and viscosity also are increased. Therefore, a solvent having alow viscosity and freezing point such as dimethoxyethane is preferablein terms of the low-temperature characteristics of a battery. However,due to a low boiling point, such a solvent increases the pressure in thebattery at a temperature higher than 100° C. As a result, in the case ofusing a general-purpose olefin type packing, a solvent is more likely todissipate through the packing. In the case of a packing using aheat-resistant resin, gas accumulates in a battery, and the battery islikely to expand due to an increase in pressure.

[0022] In contrast, when a solvent having a high boiling point such asdiethoxyethane and diglime is used, an increase in internal pressure ofa battery is suppressed, and the expansion of the battery is preventedwhen stored at a high temperature, whereby storage characteristics canbe enhanced.

[0023] In the case where the above-mentioned carbonic ester and etherare mixed, the mixing ratio thereof preferably is in a range of 30:70 to70:30 (carbonic ester:ether) in a volume ratio. A cyclic carbonic esterand a chain carbonic ester also may be mixed.

[0024] In the present embodiment, it is preferred to use at least onecyclic sultone derivative. In particular, as the cyclic sultonederivative to be contained in the electrolyte, 1,3-propanesultone or1,4-butanesultone is preferred.

[0025] It is desirable that the adding amount of the cyclic sultonederivative is set to be 0.5 to 5% by mass based on the total amount ofan electrolyte including the derivative. Due to the addition of thecyclic sultone derivative, a coating capable of suppressing the reactionwith the solvent of the electrolyte is formed on the surface of apositive electrode, and the generation of gas in the battery isdecreased to suppress the expansion of the battery. If the amount of thecyclic sultone derivative is 0.5% by mass or more, this effect isexhibited sufficiently. Furthermore, when the amount of the cyclicsultone derivative is increased, although the effect of suppressing theexpansion of a battery is enhanced, the resistance in the battery isincreased, resulting in a decrease in closed-circuit voltage (CCV).Simultaneously with this, the volume also becomes likely to decrease.Therefore, it is desirable that the adding amount is set to be 5% bymass or lower based on the total amount of the electrolyte. Inparticular, when the adding amount of the cyclic sultone derivative is3% by mass or less, discharge characteristics become satisfactory.

[0026] Examples of the acid anhydride include mellitic anhydride,malonic anhydride, maleic anhydride, butyric anhydride, propionicanhydride, pulvic anhydride, phthalonic anhydride, phthalic anhydride,pyromellitic anhydride, lactic anhydride, naphthalic anhydride, toluicanhydride, thiobenzoic anhydride, diphenic anhydride, citraconicanhydride, diglycolamidic anhydride, acetic anhydride, succinicanhydride, cinnamic anhydride, glutaric anhydride, glutaconic anhydride,valeric anhydride, itaconic anhydride, isobutyric anhydride, isovalericanhydride, and benzoic anhydride. These acid anhydrides may be usedalone or in combination of at least two kinds.

[0027] It is desirable that the adding amount of acid anhydride also isset to be 0.5 to 5% by mass based on the total amount of the electrolyteincluding the acid anhydride, in the same way as in the cyclic sultonederivative. Furthermore, in order to obtain satisfactory dischargecharacteristics, it is desirable that the adding amount of the acidanhydride is set to be 3% by mass or less.

[0028] Herein, in the case of adding both the cyclic sultone derivativeand the acid anhydride, even the addition of a small amount can suppressthe generation of gas effectively. Therefore, in this case, the problemof a decrease in load characteristics caused by an additive can bereduced. Furthermore, due to the presence of both the additives, it isexpected that the effects of them can be enhanced, and both the sideeffects can be suppressed. For example, in the case where the acidanhydride is present in an electrolyte, the acid anhydride reacts withwater in the electrolyte to generate an acid. The acid further reactswith a negative electrode to form a coating on the surface of thenegative electrode in the form of a lithium salt or the like, therebyallowing the load characteristics to be decreased easily. However, it isconsidered that such a reaction is inhibited due to the presence of thecyclic sultone derivative in the electrolyte.

[0029] In the case of adding both the cyclic sultone derivative and theacid anhydride, preferably, each adding amount should be set to be 0.3to 3% by mass. It is desirable that at least one adding amount is set tobe 0.5% by mass or more, and it is more desirable that each addingamount is set to be 0.5% by mass. Furthermore, by setting the totaladding amount to be 1.7 to 3.5% by mass, the above-mentioned cooperatedeffects can be enhanced further.

[0030] Examples of an electrolyte salt to be dissolved in theabove-mentioned electrolyte include at least one lithium salt(hereinafter, referred to as a “lithium salt A”) selected from LiBF₄,LiPF₆, LiAsF₆, and LiSbF₆, and at least one lithium salt (hereinafter,referred to as a “lithium salt B”), e.g., LiClO₄, LiC_(n)F_(2n+1)SO₃such as LiCF₃SO₃ and LiC₄F₉SO₃, LiN(CF₃SO₂)₂, LiN(C₂F₅SO₂)₂,LiC(CF₃SO₃)₃, LiCF₃CO₂, LiB₁₀Cl₁₀, lower fatty acid lithium, LiAlCl₄,CiCl, LiBr, LiI, chloroboranelithium, lithium tetraphenylborate, and thelike. In the case where manganese dioxide is used as a positive activematerial, due to the coexistence thereof, a lithium imide salt (e.g.,LiClO₄, LiC_(n)F_(2n+1)SO₃ such as LiCF₃SO₃, and LiC₄F₉SO₃,LiN(CF₃SO₂)₂, LiN(C₂F₅SO₂)₂, and the like) preferably is used.

[0031] The concentration of the electrolyte salt in the electrolyte isnot particularly limited. However, the concentration is preferably 0.2to 2 mol/dm³, more preferably 0.3 to 1.5 mol/dm³.

[0032] Furthermore, by using the mixture of the above-mentioned lithiumsalt A and lithium salt B, the effects of the above-mentioned additivesare likely to be exhibited even in a battery that has been discharged tosome degree. Furthermore, the generation of gas can be suppressedsufficiently when such a battery is stored. In this case, the proportionof the lithium salt A should be set to be 2 mol % or more based on thetotal amount of the electrolyte salt. On the other hand, the lithiumsalt A is likely to be decomposed by a trace amount of water present ina battery. Therefore, the proportion of the lithium salt A desirably isset to be 20 mol % or less based on the total amount of the electrolytesalt.

[0033] Considering the characteristics of a battery as a whole, LiBF₄ orLiPF₆ preferably is used as the lithium salt A, and at least oneselected from LiClO₄, LiCF₃SO₃, LiC₄F₉SO₃, LiN(CF₃SO₂)₂, andLiN(C₂F₅SO₂)₂ preferably is used.

[0034] In the present embodiment, as the positive active material, thosewhich are used generally as a positive active material of a lithiumprimary battery, a lithium ion secondary battery, or the like can beused. For example, in addition to LiCoO₂, LiNiO₂, andLiNi_(x)Co_(1−x)O₂, a manganese-containing oxide such as LiMnO₂, LiMnO₂,LiNi_(x)Mn_(1−x)O₂, LiMn₃O₆ and manganese dioxide, and fluorocarbon canbe used. In particular, when manganese dioxide which is highly reactivewith the electrolyte, is used, the effects of the present embodiment areexhibited conspicuously. For producing a positive electrode, generally,a conductive assistant and a binder are used in addition to the positiveactive material. As the conductive assistant, carbon black, scalelikegraphite, ketchen black, acetylene black, fibrous carbon, and the likeare used. As the binder, for example, polytetrafluoroethylene,polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadienerubber, and the like are used.

[0035] For producing a positive electrode, a positive electrode mixtureprepared by mixing a positive active material, a conductive assistant,and a binder is subjected to pressure forming. Alternatively, thepositive electrode mixture is dispersed in water or an organic solventto prepare a paste containing the positive electrode mixture, and thispaste is applied to a current collector made of a metal foil, expandedmetal, a plain-woven mesh, or the like, followed by drying and pressureforming. The method for producing a positive electrode is not limited tothe above-mentioned method. Other methods may be used.

[0036] There is no particular limit to a negative active material. Thosewhich are used as a negative active material of a lithium primarybattery, a lithium ion secondary battery, or the like can be used.Preferable specific examples thereof include metal lithium, a lithiumalloy such as lithium-aluminum, lithium-lead, lithium-bismuth,lithium-indium, lithium-gallium and lithium-indium-gallium, a carbonmaterial, and a metal oxide such as lithium titanium oxide. Thesenegative active materials can be used alone as a negative electrode.Alternatively, in the same way as in the positive electrode, a negativeelectrode mixture is prepared, and the mixture is applied to a currentcollector, followed by drying and pressure forming. In the case of usingmetal lithium, a lithium alloy, or the like, the resultant mixture maybe crimped onto a current collector made of a metal foil, a metal net,or the like.

[0037] As a separator, any of a microporous resin film and resinnon-woven fabric can be used. Examples thereof include polyolefin suchas polyethylene, polypropylene, and polymethylpentene. In addition, forthe purpose of heat resistance, fluorine resin such as atetrafluoroethylene-perfluoroalkoxyethylene copolymer, polyphenylenesulfide, polyether ether ketone, polybutylene terephthalate, and thelike are used. Furthermore, by using a separator with a layeredstructure obtained by stacking a plurality of microporous films andnon-woven fabrics made of the above materials, stacking a plurality ofmiroporous films, or stacking a plurality of non-woven fabrics,reliability in the case of use in a high-temperature atmosphere can beenhanced.

[0038] The above-mentioned positive electrode, negative electrode,electrolyte, and separator are sealed in a battery case made of a metalcan, a laminate film, or the like, whereby a non-aqueous electrolytebattery is assembled. In the case of sealing the battery case by using apacking as a sealing member, as the material for the packing, forexample, polypropylene and nylon can be used. In addition, for thepurpose of heat resistance, a heat-resistant resin having a meltingpoint higher than 240° such as fluorine resin (e.g., atetrafluoroethylene-perfluoroalkoxyethylene copolymer), polyphenyleneether, polysulfone, polyarylate, polyether sulfone, polyphenylenesulfide, polyether ether ketone, and the like can be used. Furthermore,as the sealing member, glass hermetic seal also can be used. The glasshermetic seal is a sealing member using soda-lime glass. The glasshermetic seal is applied, in a molten state, to a metal material so asto be bonded thereto, thereby sealing the metal material. The glasshermatic seal is excellent in hermeticity.

[0039] Hereinafter, various embodiments will be described specificallyby way of examples.

[0040] In one embodiment, a non-aqueous electrolyte primary battery wasproduced as follows. First, manganese dioxide as a positive activematerial, carbon black as a conductive assistant,polytetrafluoroethylene as a binder were prepared, and they were mixedin a mass ratio of 90:5:5 to obtain a positive electrode mixture. Then,the positive electrode mixture was subjected to pressure forming toproduce a positive electrode. As a negative electrode, a lithium foilwas used. As a separator, a layered structure of a microporouspolypropylene film and polypropylene non-woven fabric was used. As asealing member, a packing made of polyphenylene sulfide was used. As aresult, a coin-type non-aqueous electrolyte battery with a thickness of5 mm and a diameter of 24 mm having a configuration shown in FIG. 1 wasassembled.

[0041]FIG. 1 shows an exemplary battery, in accordance with one aspectof the present invention. A positive electrode 1 is accommodated in apositive electrode can 4 made of stainless steel, and a negativeelectrode 2 is placed on the positive electrode 1 via a separator 3. Thenegative electrode 2 is made of a lithium foil, and is crimped onto theinner surface of a negative electrode can 5 made of stainless steel. Anon-aqueous electrolyte is injected into the battery in an amount of 0.5cm³, and an opening end of the positive electrode can 4 is compressedinward, whereby an annular packing 6 made of polyphenylene sulfideprovided on the periphery of the negative electrode can 5 is pressed. Asa result, the periphery of the negative electrode can 5 is in contactwith the inner peripheral surface of the opening end of the positiveelectrode can 4 under pressure, whereby the opening of the positiveelectrode can 4 is sealed.

EXAMPLE 1

[0042] First, propylene carbonate and 1,2-dimethoxyethane were mixed ina volume ratio of 1:1 to obtain a mixed solvent. LiClO₄ was dissolved inthe mixed solvent in an amount of 0.5 mol/dm³. Then, 1,3-propanesultoneand phthalic anhydride were added to the resultant mixed solvent so thatthe contents thereof respectively became 0.5% by mass to obtain anelectrolyte. The electrolyte thus obtained was used for a battery withthe above-mentioned configuration, whereby a non-aqueous electrolytebattery of Example 1 was produced.

EXAMPLES 2-13

[0043] Non-aqueous electrolyte batteries as shown in Table 1 wereproduced in the same way as in Example 1, except that one or bothcontents of 1,3-propanesultone and phthalic anhydride were varied in arange of 0.5 to 4% by mass.

Comparative Example 1

[0044] A non-aqueous electrolyte battery was produced in the same way asin Example 1, except that 1,3-propanesultone and phthalic anhydride werenot added to the electrolyte.

Comparative Examples 2-9

[0045] Non-aqueous electrolyte batteries shown in Table 1 were producedin the same way as in Example 1, except that the adding amount of1,3-propanesultone or phthalic anhydride was set to be a value outsideof the range of the present invention. TABLE 1 Additive (% by mass)Concentration of electrolyte salt Proportion Cyclic (mol/dm³) of lithiumsultone Acid Lithium salt A Lithium salt B salt A derivative anhydrideTotal LiPF₆ LiBF₄ LiClO₄ (mol %) Example 1 0.5 0.5 1 0 0 0.5 0 Example 20.5 1 1.5 0 0 0.5 0 Example 3 1 0.5 1.5 0 0 0.5 0 Example 4 1 1 2 0 00.5 0 Example 5 0.5 2 2.5 0 0 0.5 0 Example 6 0.5 2.5 3 0 0 0.5 0Example 7 1 2 3 0 0 0.5 0 Example 8 2 1 3 0 0 0.5 0 Example 9 0.5 3 3.50 0 0.5 0 Example 10 1.5 2 3.5 0 0 0.5 0 Example 11 2 1.5 3.5 0 0 0.5 0Example 12 1 3 4 0 0 0.5 0 Example 13 3 1 4 0 0 0.5 0 Comparative 0 0 00 0 0.5 0 Example 1 Comparative 1 0 1 0 0 0.5 0 Example 2 Comparative 01 1 0 0 0.5 0 Example 3 Comparative 0 4 4 0 0 0.5 0 Example 4Comparative 4 0 4 0 0 0.5 0 Example 5 Comparative 1 0.2 1.2 0 0 0.5 0Example 6 Comparative 0.2 1 1.2 0 0 0.5 0 Example 7 Comparative 1 4 5 00 0.5 0 Example 8 Comparative 4 1 5 0 0 0.5 0 Example 9

[0046] The batteries of Examples 1-13 and Comparative Examples 1-9 afterstored at 120° C. for 350 hours were examined for load characteristicsat a low temperature, expansion of a battery, and a capacity retentionratio. Table 2 shows the results. Methods for measuring the loadcharacteristics at a low temperature, the expansion of a battery, andthe capacity retention ratio are as follows.

[0047] Load Characteristics at a Low Temperature:

[0048] After stored at 120° C. for 350 hours, a battery was dischargedat −40° C. and a current value of 2 mA, and a CCV after 5 seconds fromthe commencement of the discharge was measured.

[0049] Expansion of a Battery:

[0050] A battery was stored at 120° C. for 350 hours and allowed to coolto 20° C., and then, the thickness of the battery was measured. A valueobtained by subtracting the thickness of the battery previously measuredbefore storage from the thickness measured after cooling was determinedas the expansion of the battery.

[0051] Capacity Retention Ratio:

[0052] First, a battery before stored at a high temperature wasconnected to a discharge resistor of 1 kΩ, and discharged at 20° C. to atermination voltage of 2.0 V. A discharge capacity at this time wasmeasured. Another battery was stored at 120° C. for 350 hours andallowed to cool to 20° C. The battery was discharged under the samecondition as that before storage, and a discharge capacity at this timewas measured. The ratio of the discharge capacity thus obtained to thatbefore storage was determined as a capacity retention ratio. TABLE 2 CCVat −40° C. (V) Capacity After 5 seconds Expansion of retention from thedischarge battery ratio at 2 mA (mm) (%) Example 1 2.92 0.30 90 Example2 2.95 0.25 92 Example 3 2.94 0.24 92 Example 4 2.92 0.15 94 Example 52.90 0.09 93 Example 6 2.88 0.06 92 Example 7 2.95 0.10 95 Example 82.89 0.12 94 Example 9 2.85 0.06 91 Example 10 2.85 0.10 93 Example 112.80 0.08 94 Example 12 2.65 0.05 87 Example 13 2.60 0.05 89 Comparative1.90 0.80 67 Example 1 Comparative 2.77 0.45 77 Example 2 Comparative2.80 0.40 79 Example 3 Comparative 2.52 0.09 80 Example 4 Comparative2.49 0.10 77 Example 5 Comparative 2.81 0.41 82 Example 6 Comparative2.81 0.42 83 Example 7 Comparative 2.33 0.04 84 Example 8 Comparative2.24 0.03 85 Example 9

[0053] As is apparent from Table 2, the batteries of Examples 1-13, withthe cyclic sultone derivative and the acid anhydride added to anelectrolyte in an amount of 0.5 to 3% by mass, had a high dischargevoltage, less expanded when stored at a high temperature, and had a highcapacity retention ratio. Thus, these batteries were suitable for use ina high-temperature atmosphere. Particularly, in the batteries ofExamples 4-11 in which the total adding amount of the cyclic sultonederivative and the acid anhydride was 2 to 3.5% by mass, the generationof gas in a battery was reduced to suppress the expansion of the batteryeffectively while minimizing a decrease in discharge voltage, i.e., adecrease in load characteristics.

[0054] In contrast, the battery of Comparative Example 1, with no cyclicsultone derivative and acid anhydride added to an electrolyte, expandedlargely when stored at a high temperature, and a discharge voltage wasdecreased remarkably and a capacity retention ratio was low.Furthermore, in the batteries of Comparative Examples 2-5 with eitherone of the cyclic sultone derivative and the acid anhydride added to anelectrolyte, the effect of suppressing the expansion of a battery wasnot sufficient, or a decrease in discharge voltage was large. Thus,satisfactory storage characteristics were not obtained.

[0055] Furthermore, in the batteries of Comparative Examples 6-9 inwhich the cyclic sultone derivative and the acid anhydride were added toan electrolyte in an amount outside the range of the present invention,the effect of the coexistence of the additives was not sufficient, or adecrease in discharge voltage due to the addition of the additivesexceeding a required amount was conspicuous. Thus, satisfactory storagecharacteristics were not obtained.

EXAMPLE 14

[0056] A non-aqueous electrolyte battery was produced in the same way asin Example 1, except that 0.5 mol/dm³ of LiClO₄ and 0.05 mol/dm³ ofLiPF₆ were dissolved in a mixed solvent of propylene carbonate and1,2-dimethoxyethane (1:1 in a volume ratio), and 1,3-propanesultone andphthalic anhydride were added in an amount of 0.5% by mass,respectively, to the mixture, thereby obtaining an electrolyte.

EXAMPLES 15-17

[0057] A non-aqueous electrolyte battery shown in Table 3 was producedin the same way as in Example 14, except that the adding amount of anadditive and the kind and concentration of an electrolyte salt werevaried.

EXAMPLE 18

[0058] A non-aqueous electrolyte battery shown in Table 3 was producedin the same way as in Example 17, except that LiClO₄ was used alone asan electrolyte salt, and lithium salt A was not contained.

Comparative Example 10

[0059] A non-aqueous electrolyte battery was produced in the same way asin Example 16, except that the cyclic sultone derivative and the acidanhydride were not added to the electrolyte. TABLE 3 Concentration ofelectrolyte salt Additive (% by mass) (mol/dm³) Proportion CyclicLithium salt of lithium sultone Acid Lithium salt A salt B salt Aderivative anhydride Total LiPF₆ LiBF₄ LiClO₄ (mol %) Example 14 0.5 0.51 0.05 0 0.5 9.1 Example 15 2 1 3 0 0.05 0.5 9.1 Example 16 2 1 3 0.1 00.5 16.7 Example 17 1.5 1.5 3 0.03 0 0.4 7.0 Example 18 1.5 1.5 3 0 00.5 0 Comparative 0 0 0 0.1 0 0.5 16.7 Example 10

[0060] The batteries of Examples 14-18 and Comparative Example 10 wereexamined for the expansion of a battery after stored at a hightemperature when a discharge depth was 50% and 80%. Table 4 shows theresults. A method for measuring the expansion of a battery is asfollows.

[0061] Expansion of Batteries:

[0062] A battery was discharged until a discharge depth became 50%, andanother battery was discharged until a discharge depth became 80%.Thereafter, these batteries were stored at 120° C. for 350 hours andallowed to cool to 20° C. The thickness of each battery at this time wasmeasured. A value obtained by subtracting the thickness of each batterypreviously measured before storage from the thickness measured aftercooling was determined as the expansion of each battery. TABLE 4Expansion of battery (mm) Discharge by 50% Discharge by 80% Example 140.20 0.15 Example 15 0.20 0.08 Example 16 0.15 0.05 Example 17 0.20 0.10Example 18 0.20 0.70 Comparative 0.55 0.10 Example 10

[0063] As shown in Table 4, the batteries of Examples 14-17 lessexpanded even when stored after the discharge has proceeded, and thegeneration of gas was suppressed sufficiently. More specifically, in thebatteries of Examples 14-17, a mixture of lithium salt A such as LiPF₆and LiBF₄ and at least one lithium salt B other than the lithium salt Awas used as an electrolyte salt for a non-aqueous electrolyte. Thelithium salt A was contained in an amount of 2 mol % or more based onthe total amount of the electrolyte salt, and at least one of the cyclicsultone derivative and the acid anhydride was added to the electrolyte,whereby the effect of the additive was maintained irrespective of adischarge depth.

[0064] In contrast, the battery of Comparative Example 10 expandedlargely when stored at a relatively small discharge depth. Furthermore,the battery of Example 18 has substantially the same electrolytecomposition as that of Example 10 or 11; however, the additive exhibitedits effect effectively at a relatively small discharge depth, while theeffect of the additive was eliminated when discharge has proceeded,allowing the battery to expand largely.

[0065] As described in Examples 14-17, when LiPF₆, LiBF₄, and the likeare contained, the generation of gas can be suppressed when a battery isstored at a high temperature after discharge has proceeded. The reasonfor this is not made clear. However, it is presumed that PF₅ and BF₃derived from an electrolyte salt react with a new phase of a negativeactive material formed due to discharge, and a coating of a fluoride isformed on the surface of the active material, whereby decomposition ofan ester and ether of the electrolyte solvent is suppressed.

EXAMPLE 19

[0066] A non-aqueous electrolyte battery shown in Table 5 was producedin the same way as in Example 1, except that 0.5 mol/dm³ of LiClO₄ wasdissolved in a mixed solvent of propylene carbonate and diethoxyethane(1:1 in a volume ratio), and 1,3-propanesultone was added to theresultant mixture in an amount of 2% by mass to obtain an electrolyte,and a packing made of a tetrafluoroethylene-perfluoroalkoxyethylenecopolymer was used.

EXAMPLE 20

[0067] A non-aqueous electrolyte battery was produced in the same way asin Example 19, except that diglime was used in place of diethoxyethane.

EXAMPLE 21

[0068] A non-aqueous electrolyte battery was produced in the same way asin Example 19, except that 1,3-propanesultone was added to theelectrolyte in an amount of 0.5% by mass.

EXAMPLE 22

[0069] A non-aqueous electrolyte battery was produced in the same way asin Example 19, except that 1,3-propanesultone was added to theelectrolyte in an amount of 5% by mass.

Comparative Example 11

[0070] A non-aqueous electrolyte battery was produced in the same way asin Example 19, except that dimethoxyethane was used in place ofdiethoxyethane.

Comparative Example 12

[0071] A non-aqueous electrolyte battery was produced in the same way asin Comparative Example 11, except that a packing made of polypropylenewas used.

Comparative Example 13

[0072] A non-aqueous electrolyte battery was produced in the same way asin Comparative Example 11, except that 1,3-propanesultone was not addedto the electrolyte.

Comparative Example 14

[0073] A non-aqueous electrolyte battery was produced in the same way asin Comparative Example 11, except that 1,3-propanesultone was added tothe electrolyte in an amount of 10% by mass. TABLE 5 Adding amount ofcyclic Material sultone derivative for packing Electrolyte solvent (% bymass) Example 19 PFA Propylene carbonate + 2 diethoxyethane Example 20PFA Propylene carbonate + diglime 2 Example 21 PFA Propylene carbonate +0.5 diethoxyethane Example 22 PFA Propylene carbonate + 5 diethoxyethaneComparative PFA Propylene carbonate + 2 Example 11 dimethoxyethaneComparative PP Propylene carbonate + 2 Example 12 dimethoxyethaneComparative PFA Propylene carbonate + 0 Example 13 dimethoxyethaneComparative PFA Propylene carbonate + 10 Example 14 dimethoxyethane

[0074] The batteries of Examples 19-22 and Comparative Examples 11-14were examined for load characteristics at a room temperature, expansionof a battery, and a capacity retention ratio after stored at 120° C. for200 hours. Table 6 shows the results. Methods for measuring the loadcharacteristics at a room temperature, the expansion of a battery, andthe capacity retention ratio are as follows.

[0075] Load Characteristics at a Room Temperature:

[0076] After stored at 120° C. for 200 hours, a battery was connected toa discharge resistor of 200Ω and discharged at 20° C. and a CCV after 5seconds from the commencement of the discharge was measured.

[0077] Expansion of a Battery:

[0078] A battery was stored at 120° C. for 200 hours and allowed to coolto 20° C., and then, the thickness of the battery was measured. A valueobtained by subtracting the thickness of the battery previously measuredbefore storage from the thickness measured after cooling was determinedas the expansion of the battery.

[0079] Capacity Retention Ratio:

[0080] First, a battery before stored at a high temperature wasconnected to a discharge resistor of 3.9Ω, and discharged at 20° C. to atermination voltage of 2.0 V. A discharge capacity at this time wasmeasured. Another battery was stored at 120° C. for 200 hours andallowed to cool to 20° C. The battery was discharged under the samecondition as that before storage, and a discharge capacity at this timewas measured. The ratio of the discharge capacity thus obtained to thatbefore storage was determined as a capacity retention ratio. TABLE 6 CCVat 20° C. Capacity (V) retention After 5 seconds from Expansion ofbattery ratio discharge at 200 Ω (mm) (%) Example 19 2.93 0.11 97Example 20 2.90 0.08 96 Example 21 2.95 0.13 95 Example 22 2.89 0.06 96Comparative 2.95 0.15 97 Example 11 Comparative 2.23 0.20 72 Example 12Comparative Example 13 1.90 0.80 70 Comparative 2.05 0.03 78 Example 14

[0081] As is apparent from Table 6, the batteries of Examples 19-22, inwhich an ether having a boiling point of 120° C. or higher was containedas an electrolyte solvent, a cyclic sultone derivative was added to theelectrolyte in an amount of 0.5 to 5% by mass, and sealing was conductedwith a packing made of a heat-resistant resin, had a high dischargevoltage, less expanded when stored at a high temperature, and had a highcapacity retention ratio. Thus, these batteries were suitable for use ina high-temperature atmosphere.

[0082] In contrast, the battery of Comparative Example 11, in whichdimethoxyethane having a boiling point of 84° C. was contained in placeof an ether having a boiling point of 120° C. or higher, exhibited loadcharacteristics enhanced to some degree; however, it expanded largely toincrease the inner pressure therein.

[0083] Furthermore, the battery of Comparative Example 12, in which apacking made of polypropylene was used in place of the packing inComparative Example 11, expanded largely when stored at a hightemperature compared with Comparative Example 11 and had a substantiallylow discharge voltage and capacity retention ratio. The reason for thisis considered as follows: the sealing performance of the battery wasdecreased, causing the electrolyte solvent to dissipate out of thebattery and water to enter the battery.

[0084] Furthermore, in the battery of Comparative Example 13 with nocyclic sultone derivative added thereto or the battery of ComparativeExample 14 with an excess amount of cyclic sultone derivative addedthereto, a decrease in discharge voltage was conspicuous. Thus,satisfactory storage characteristics were not obtained.

[0085] The invention may be embodied in other forms without departingfrom the spirit or essential characteristics thereof. The embodimentsdisclosed in this application are to be considered in all respects asillustrative and not limiting. The scope of the invention is indicatedby the appended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

What is claimed is:
 1. A non-aqueous electrolyte battery comprising apositive electrode, a negative electrode, a separator, and a non-aqueouselectrolyte, wherein the non-aqueous electrolyte comprises a lithiumsalt, a cyclic sultone derivative, and an acid anhydride, thenon-aqueous electrolyte contains the cyclic sultone derivative in anamount of 0.3 to 3% by mass, and the non-aqueous electrolyte containsthe acid anhydride in an amount of 0.3 to 3% by mass.
 2. The non-aqueouselectrolyte battery according to claim 1, wherein the non-aqueouselectrolyte contains the cyclic sultone derivative in an amount of 0.5to 3% by mass.
 3. The non-aqueous electrolyte battery according to claim1, wherein the non-aqueous electrolyte contains the acid anhydride in anamount of 0.5 to 3% by mass.
 4. The non-aqueous electrolyte batteryaccording to claim 1, wherein the non-aqueous electrolyte contains thecyclic sultone derivative in an amount of 0.5 to 3% by mass and the acidanhydride in an amount of 0.5 to 3% by mass.
 5. The non-aqueouselectrolyte battery according to claim 4, wherein the non-aqueouselectrolyte contains the cyclic sultone derivative and the acidanhydride in an amount of 1.7 to 3.5% by mass.
 6. The non-aqueouselectrolyte battery according to claim 1, wherein the cyclic sultonederivative comprises at least one selected from the group consisting of1,3-propanesultone and 1,4-butanesultone.
 7. The non-aqueous electrolytebattery according to claim 1, wherein the positive electrode contains apositive active material, and the positive active material comprises amanganese-containing oxide.
 8. The non-aqueous electrolyte batteryaccording to claim 1, wherein the negative electrode contains a negativeactive material, and the negative active material comprises one selectedfrom the group consisting of lithium and a lithium alloy.
 9. Thenon-aqueous electrolyte battery according to claim 1, further comprisinga sealing member, wherein the sealing member comprises a packing made ofa heat-resistant resin or glass hermetic seal.
 10. The non-aqueouselectrolyte battery according to claim 9, wherein the packing comprisesat least one selected from the group consisting of atetrafluoroethylene-perfluoroalkoxyethylene copolymer, polyphenylenesulfide, and polyether ether ketone.
 11. The non-aqueous electrolytebattery according to claim 1, wherein the non-aqueous electrolytecontains a solvent, and the solvent comprises at least one ether havinga boiling point of 120° C. or higher.
 12. A non-aqueous electrolytebattery comprising a positive electrode, a negative electrode, aseparator, and a non-aqueous electrolyte, wherein the non-aqueouselectrolyte contains at least one selected from the group consisting ofa cyclic sultone derivative and an acid anhydride, and an electrolytesalt, the electrolyte salt comprises lithium salt A and lithium salt B,the lithium salt A comprises at least one selected from the groupconsisting of LiBF₄, LiPF₆, LiAsF₆, and LiSbF₆, and the lithium salt Bcomprises a lithium salt other than the lithium salt A, and theelectrolyte salt contains the lithium salt A in an amount of 2 mol % ormore.
 13. The non-aqueous electrolyte battery according to claim 12,wherein the electrolyte salt contains the lithium salt A in an amount of2 to 20 mol %.
 14. The non-aqueous electrolyte battery according toclaim 12, wherein the lithium salt B is at least one selected from thegroup consisting of LiClO₄, LiCF₃SO₃, LiC₄F₉SO₃, LiN(CF₃SO₂)₂, andLiN(C₂F₅SO₂)₂.
 15. The non-aqueous electrolyte battery according toclaim 12, wherein the non-aqueous electrolyte contains the cyclicsultone derivative in an amount of 0.5 to 3% by mass.
 16. Thenon-aqueous electrolyte battery according to claim 12, wherein thenon-aqueous electrolyte contains the acid anhydride in an amount of 0.5to 3% by mass.
 17. The non-aqueous electrolyte battery according toclaim 12, wherein the non-aqueous electrolyte contains the cyclicsultone derivative in an amount of 0.5 to 3% by mass and the acidanhydride in an amount of 0.5 to 3% by mass.
 18. The non-aqueouselectrolyte battery according to claim 17, wherein the non-aqueouselectrolyte contains the cyclic sultone derivative and the acidanhydride in an amount of 1.7 to 3.5% by mass.
 19. The non-aqueouselectrolyte battery according to claim 12, wherein the cyclic sultonederivative comprises at least one selected from the group consisting of1,3-propanesultone and 1,4-butanesultone.
 20. The non-aqueouselectrolyte battery according to claim 12, wherein the positiveelectrode contains a positive active material, and the positive activematerial comprises a manganese-containing oxide.
 21. The non-aqueouselectrolyte battery according to claim 12, wherein the negativeelectrode contains a negative active material, and the negative activematerial comprises one selected from the group consisting of lithium anda lithium alloy.
 22. The non-aqueous electrolyte battery according toclaim 12, further comprising a sealing member, wherein the sealingmember comprises a packing made of a heat-resistant resin or glasshermetic seal.
 23. The non-aqueous electrolyte battery according toclaim 22, wherein the packing comprises at least one selected from thegroup consisting of a tetrafluoroethylene-perfluoroalkoxyethylenecopolymer, polyphenylene sulfide, and polyether ether ketone.
 24. Thenon-aqueous electrolyte battery according to claim 12, wherein thenon-aqueous electrolyte contains a solvent, and the solvent contains anether having a boiling point of 120° C. or higher.
 25. A non-aqueouselectrolyte battery comprising a positive electrode, a negativeelectrode, a separator, a non-aqueous electrolyte, and a sealing member,wherein the non-aqueous electrolyte comprises a solvent and a cyclicsultone derivative, the solvent contains an ether having a boiling pointof 120° C. or higher, the non-aqueous electrolyte contains the cyclicsultone derivative in an amount of 0.5 to 5% by mass, and the sealingmember comprises a packing made of a heat-resistant resin or glasshermetic seal.